Digital information, including computer-readable program code, text, and multimedia (e.g., graphics, audio, video), to name a few, continues to proliferate. Therefore, storage media, and devices for recording and reading the storage media, are continually being developed and enhanced for storing and accessing digital information.
Digital information is typically organized on removable storage media in the form of sectors. A removable storage medium may comprise a number of physical sectors, at least a portion of which may be further represented as logical sectors. Digital information is organized on the logical sectors of the removable storage media according to a file system (e.g., International Organization for Standardization's ISO 9660 file structure standard, Universal Disk Format (UDF), variations thereof, etc.). Typically, a file system indicator (e.g., an anchor volume descriptor pointer (AVDP) for a UDF file system) is written at a standard location on the removable storage medium and indicates additional file system information for the removable storage medium. By way of example, when the removable storage medium is loaded into a device for reading the digital information stored thereon, the device detects the file system indicator (e.g., the UDF AVDP) at the standard location (e.g., for DVD, physical sector number (PSN) “30100”,logical sector number (LSN) “256”) on the removable storage medium, which indicates additional file system information. The device may then use software and/or firmware to access the digital information according to the file system.
Information on read-only storage media, such as DVD-ROM (read-only-memory) discs, is initially recorded using a standard file system (e.g., UDF). Most appliances (e.g., DVD players) and computer drives (e.g., DVD drives) readily recognize the standard file system. Digital information on a read-only storage medium cannot be modified. As such, the use of read-only removable storage media is limited to digital information that does not require modification. For example, read-only removable storage media may be used for distribution of video recordings, software applications, and data, to name a few.
Rewritable storage media, such as DVD+RW (rewritable) discs, on the other hand, are formatted to read, write or record, and modify (e.g., rewrite, erase, etc.) digital information thereon. Digital information may be read, recorded, and modified on the rewritable storage media using suitable software and/or firmware. The software and/or firmware may also allow the media to be configured for defect management. That is, when an area on the media is damaged or worn from repeated use, the digital information for that area may instead be written to another area on the removable storage media and the media may be “remapped” (e.g., reassigning the logical sectors to different physical sectors). This causes some digital information intended to occur in consecutive physical sectors to be recorded in non-consecutive sectors even though it still appears as consecutive logical sectors to the file system.
Accordingly, a device that is “unaware” of the disc configuration may have difficulty reading a removable storage medium that has been remapped by a device that is “aware” of the disc configuration. That is, some types of data require physically consecutive sectors on the storage medium (e.g., video data). However, digital information may not be stored on consecutive sectors where the removable storage medium has been remapped for defect management. In addition, unaware devices typically are not readily upgraded with software or firmware for reading removable storage media that has been remapped. As such, the unaware device may be unable to read, or may misread, the correct digital information from the removable storage medium so configured.